Re: [PATCH bpf v3] selftests/bpf: Check returned keys in map batch validators

[Tianyi Chen <diannaaav@gmail.com>]

These files run under test_maps, not test_progs. They include test_maps.h,
whose CHECK() reports the failure and calls exit(-1). That header does
not provide ASSERT_*(). The suggested ASSERT_GE/LT/LE helpers are defined
in test_progs.h and depend on that runner's failure reporting.

The distinction matters for these range checks: execution must stop
before indexing visited with an invalid returned key. ASSERT_*() returns
a boolean and does not itself stop the caller, so a mechanical replacement
would not preserve that behavior, even after resolving the runner/header
dependencies.

I am retaining CHECK() for this targeted test_maps correctness fix.
Migrating these tests to the test_progs assertion framework would be a
separate change requiring compatible failure reporting and control flow.
The current v3 passed test_maps with no skips on the rebuilt bpf/master
kernel (7.3.0-rc2).

Thanks,
Tianyi